Summary The 13C isotopic signature (δ13C) of CO2 respired from plants is widely used to assess carbon fluxes and ecosystem functioning. There is, however, a lack of knowledge of the metabolic basis of the δ13C value of respired CO2. To elucidate the physiological mechanisms driving 12C/13C fractionation during respiration, the δ13C of respired CO2 from dark‐acclimated leaves during the night, from darkened leaves during the light period, and from stems and roots of Ricinus communis was analysed. The δ13C of potential respiratory substrates, the respiratory quotient and the activities of phosphoenolpyruvatecarboxylase (PEPc) and key respiratory enzymes were also measured. It is shown here that the CO2 evolved from darkened light‐acclimated leaves during the light period is 13C‐enriched, and that this correlates with malate accumulation in the light and rapid malate decarboxylation just after the onset of darkness. Whilst CO2 evolved from leaves was generally 13C‐enriched (but to a lesser extent during the night), CO2 evolved from stems and roots was depleted compared with the putative respiratory substrates; the difference was mainly caused by intensive PEPc‐catalysed CO2 refixation in stems and roots. These results provide a physiological explanation for short‐term variations of δ13C in CO2, illustrating the effects of variations of metabolic fluxes through different biochemical pathways.

Climatic hazards, such as severe droughts and floods, affect extensive areas across monsoon Asia and can have profound impacts on the populations of that region. The area surrounding Indonesia, including large portions of the eastern Indian Ocean and Java Sea, plays a key role in the global climate system because of the enormous heat and moisture exchange that occurs between the ocean and atmosphere there. Here, we evaluate the influence of rainfall variability on multiple treering parameters of teak (Tectona grandis) trees growing in a lowland rain forest in Central Java (Indonesia). We assess the potential of, annually resolved, tree-ring width, stable carbon ( 13 C) and oxygen ( 18 O) isotope records to improve our understanding of the Asian monsoon variability.Climate response analysis with regional, monthly rainfall data reveals that all three tree-ring parameters are significantly correlated to rainfall, albeit during different monsoon seasons. Precipitation in the beginning of the rainy season (Sep-Nov) is important for tree-ring width, confirming previous studies. Compared to ring width, the stable isotope records possess a higher degree of common signal, especially during portions of the peak rainy season (

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Measuring canopy height using satellite-based X-band interferometric SAR (InSAR) is promising for accurate monitoring of forest biomass. A prerequisite for applying this at large scale is that the penetration of the radar microwaves into the forest canopy is stable over time, i.e. not influenced by weather conditions. We investigated this in a tropical rainforest in Indonesia using 10 TanDEM-X InSAR data sets acquired during a 2-year period. We found that mean InSAR-derived canopy height varied with a standard deviation of about 0.5 m between acquisitions. The standard variation was 0.8 m; however, about 0.3 m could be attributed to errors stemming from technical properties of the acquisitions. In conclusion, this further supports the use of X-band InSAR from satellite missions for forest monitoring.

This paper evaluates the opportunity provided by global interferometric radar datasets for monitoring deforestation, degradation and forest regrowth in tropical and semi-arid environments. The paper describes an easy to implement method for detecting forest spatial changes and estimating their magnitude. The datasets were acquired within space-borne high spatial resolutions radar missions at near-global scales thus being significant for monitoring systems developed under the United Framework Convention on Climate Change (UNFCCC). The approach presented in this paper was tested in two areas located in Indonesia and Australia. Forest change estimation was based on differences between a reference dataset acquired in February 2000 by the Shuttle Radar Topography Mission (SRTM) and TanDEM-X mission (TDM) datasets acquired in 2011 and 2013. The synergy between SRTM and TDM datasets allowed not only identifying changes in forest extent but also estimating their magnitude with respect to the reference through variations in forest height.

Padang Island in Riau Province of Indonesia has been severely impacted by recurrent fires in 2014 and 2015, leading to severe peat ecosystem degradation and people´s livelihood. Therefore, analyzing the peat fires should not be isolated from socio-economic and local political context. Much has been written about peat fires  especially the magnitude of the fires, however the linkages between ecological and livelihood system of peatland ecosystem gained only scant attention. This paper analyzes how the drivers of peat fires are causing a steady decline in Padang Island and aims to provide more holistic understanding on how the drivers interplay and continue to feed the process of peatland degradation with its associated impacts on local economic development and people’s livelihood. Multidisciplinary approach was applied in this study. This includes remote sensing data analysis, analysis on related documents such as historical documents and regulations. Intensive fieldwork was conducted in the island in which series of FGDs and interviews were executed. We found that the global demands for agricultural commodities have led to massive peat drainage for monoculture farming on peat lands. The high dependency on global commodity market and monoculture farming has created livelihood vulnerability, especially because of the price fluctuation of agricultural products at global market. Moreover, the monoculture farming on peat lands tends to be unsustainable since it demands peat drainage, provides less options for sources of income and tends to marginalize indigenous knowledge about farming on peatland (paludiculture) which have been practiced for centuries in the island. Memahami Dampak Kebakaran Lahan Gambut yang Berulang di Pulau Padang-Provinsi Riau, IndonesiaIntisariPulau Padang yang terletak di Provinsi Riau, Indonesia mengalami kebakaran lahan gambut cukup parah dan berulang pada tahun 2014 dan 2015 yang mengakibatkan degradasi ekosistem gambut dan kehidupan masyarakat. Oleh karena itu, seharusnya analisis kebakaran lahan gambut tidak dapat dapat dipisahkan dari konteks sosial ekonomi dan politik lokal. Sudah banyak tulisan yang menganalisis tentang kebakaran lahan gambut terutama terkait dengan besarnya kebakaran, tetapi sangat sedikit yang menganalisis hubungan antara sistem ekologi dan sistem kehidupan masyarakat. Artikel ini menganalisis bagaimana faktor-faktor penyebab kebakaran lahan gambut juga mengakibatkan degradasi yang terusmenerus di Pulau Padang dan bertujuan untuk berkontribusi pada pemahaman yang lebih menyeluruh mengenai bagaimana faktor-faktor tersebut bekerja, saling terkait, dan secara terus-menerus mempengaruhi proses degradasi lahan gambut serta dampaknya terhadap pembangunan ekonomi lokal dan kehidupan masyarakat. Penelitian ini menerapkan pendekatan multi-disiplin yang meliputi analisis data penginderaan jauh, dokumen sejarah dan peraturan terkait. Penelitian lapangan dilakukan secara intensif di Pulau Padang, meliputi serial diskusi kelompok terfokus dan wawancara. Kami menemukan bahwa permintaan pasar global akan komoditas pertanian berkontribusi terhadap drainase lahan gambut skala besar untuk pertanian monokultur pada lahan gambut. Tingginya ketergantungan terhadap pasar global komoditas dan pertanian monokultur telah menciptakan kehidupan masyarakat yang rentan. Hal ini terutama karena besarnya fluktuasi harga komoditas pertanian di pasar global. Di samping itu, pertanian monokultur pada lahan gambut cenderung tidak berkelanjutan karena mensyaratkan pengeringan lahan gambut dengan drainase, menawarkan pilihan sumber penghasilan masyarakat yang lebih sedikit dan meminggirkan pengetahuan lokal tentang paludikultur yang sudah dipraktekkan selama berabad-abad di Pulau Padang.

ABSTRACT:The capability of L-band radar backscatter to penetrate through the forest canopy is useful for mapping the forest structure, including above ground biomass (AGB) estimation. Recent studies confirmed that the empirical AGB models generated from the L-band radar backscatter can provide favourable estimation results, especially if the data has dual-polarization configuration. Using dual polarimetry SAR data the backscatter signal is more sensitive to forest biomass and forest structure because of tree trunk scattering, thus showing better discriminations of different forest successional stages. These SAR approaches, however, need to be further studied for the application in tropical peatlands ecosystem We aims at estimating forest carbon stocks and stand biophysical properties using combination of multi-temporal and multi-polarizations (quad-polarimetric) L-band SAR data and focuses on tropical peat swamp forest over Kampar Peninsula at Riau Province, Sumatra, Indonesia which is one of the most peat abundant region in the country. Applying radar backscattering (Sigma nought) to model the biomass we found that co-polarizations (HH and VV) band are more sensitive than cross-polarization channels (HV and VH). Individual HH polarization channel from April 2010 explained > 86% of AGB. Whereas VV polarization showed strong correlation coefficients with LAI, tree height, tree diameter and basal area. Surprisingly, polarimetric anisotropy feature from April 2007 SAR data show relatively high correlations with almost all forest biophysical parameters. Polarimetric anisotropy, which explains the ratio between the second and the first dominant scattering mechanism from a target has reduced at some extent the randomness of scattering mechanism, thus improve the predictability of this particular feature in estimating the forest properties. These results may be influenced by local seasonal variations of the forest as well as moisture, but available quad-pol SAR data were unable to show these patterns, since all the SAR data were acquired during the rainy season. The results of multi-regression analysis in predicting above ground biomass shows that ALOS PALSAR data acquired in 2010 has outperformed other time series data. This is probably due to the fact that land cover change in the area from 2007 -2009 was highly dynamic, converting natural forests into rubber and Acacia plantations, thus SAR data of 2010 which was acquired in between of two field campaigns has provided significant results (F = 40.7, P < 0.005). In general, we found that polarimetric features have improved the models performance in estimating AGB. Surprising results come from single HH polarization band from April 2010 that has a strong correlation with AGB (r = 0.863). Also, HH polarization band of 2009 SAR image resulted in a moderate correlation with AGB (r = 0.440).

High productivity fast growing species plantation establishment such as the line planting of red meranti (i.e Shorealeprosula and Shorea parvifolia) with intensive silviculture is one potential solution to improve wood supply for industries in Indonesia. However, the information of anatomical properties and wood properties of these two species related to the influence of the line planting system and tree growth rate is limited. This paper studies the anatomical features, wood cell proportions, fiber dimensions and physical properties of wood in radial variation in relation to the line planting effect and tree growth rate. Wood of the trees grown in the line planting system showed higher proportion of vessel element compared to those of wood from natural forest. The vessel diameter of wood from the line planting was also larger than that of in wood from natural forest. The specific gravity of wood from Shorea parvifolia grown on the line planting was higher than that of wood grown in natural forest. The variation of specific gravity on wood portion near to the pith of Shorea leprosula and Shorea parvifolia trees grown on the line planting was related to the variation of the cell wall thickness. The bigger diameter of trees grown or the faster growth rate in the line of planting at the same age shows the greater vessel diameter in wood of Shorea leprosula and Shorea parvifolia and greater specific gravity of Shorea parvifolia wood.